SHA1 in Swift 3

hmacsha1

func hmacsha1(_ data:Data!, secret key:Data!) -> Data! {
  let cHMAC = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity:Int(CC_SHA1_DIGEST_LENGTH))
  key.withUnsafeBytes {(keyBytes: UnsafePointer<UInt8>)->Void in
      data.withUnsafeBytes {(dataBytes: UnsafePointer<UInt8>)->Void in
          CCHmac(CCHmacAlgorithm(kCCHmacAlgSHA1),keyBytes, key.count, dataBytes, data.count, cHMAC)
      }
  }
  return Data(bytes:cHMAC, count:Int(CC_SHA1_DIGEST_LENGTH))
}